The present invention relates to an air flow control device for an air conditioner with an upper outlet port and a lower outlet port.
A room side unit in the conventional air conditioner as, for example, disclosed in Japanese Unexamined Patent Publication No. 191842/1984, the vertical sectional view of which is shown in FIG. 11, comprises an upper air-blowing fan 1 disposed in its upper portion, a lower air-blowing fan 2 disposed in its lower portion and a room side heat exchanger 3 arranged between both fans 1 and 2. The room side unit 7 is provided with an upper outlet port 4 in its upper front portion, a lower outlet port 5 in its lower front portion and an intake port 8 in its middle front portion. The blowing fans 1 and 2 suck air into the unit through the heat exchanger 3 and blow out the conditioned air from the outlet ports 4 and 5, as indicated by an arrow 6.
FIG. 12 is a block diagram showing an air-blowing fan control system provided in the room side unit as shown in FIG. 11. The system includes air-blowing fan operation mode determining means 11 for determining the operation modes of both air-blowing fans, air-blowing fan operation control means 12 for controlling the operations of both fans, temperature detecting means 14 for detecting the temperature of the heat exchanger, temperature detecting means 15 for detecting the temperature of outlet air, and load calculating means 16 for calculating a load based on the detection temperature signal from the temperature detecting means 14 and the detection temperature signal from the outlet air temperature detecting means 15 and sending the results to the fan operation mode determining means 11.
The operation of the system will be described in reference to FIG. 13 wherein the operation modes of the fans and the temperature of the heat exchanger are shown in graphical representations.
Even when "heating" operation starts, both fans 1 and 2 maintain their OFF mode as shown in FIG. 13 at A and B until the temperature of the heat exchanger 3 reaches a preset value A, because the temperature of the heat exchanger 3 is lower than that value immediately after the heating operation has started. When the temperature of the heat exchanger 3 reaches the value A as shown in FIG. 13 at C, the upper air-blowing fan 1 is driven in its low speed mode. When the temperature of the heat exchanger reaches a preset value B, the fan 1 is driven in its high speed mode. In addition, when the temperature of the heat exchanger 3 rises to a preset value C, the lower blowing fan 2 is driven in its low speed mode. When the temperature reaches a preset value D, the lower blowing fan 2 is driven in its high speed mode.
Now, the operation of the system will be explained in reference to FIG. 12. The detection temperature signal from the heat exchanger temperature detecting means 14 and the detection temperature signal from the outlet air temperature detecting means 15 are fed to the load calculating means 16 to calculate the load condition. The load signal representing the calculated load condition is fed to the fan operation mode determining means 11 to determine the operation modes of both fans depending on the load signal. The determined operation modes are instructed to the controlling means 12 for controlling the operations of both fans. The control means 12 controls both fans 1 and 2 in accordance with the instructed operation modes.
In the conventional air conditioners, the operations of the upper and lower air-blowing fans are controlled solely on the basis of the load being calculated from the temperatures of the room side heat exchanger and the outlet air. As a result, the conventional air conditioners can not always provide a sense of comfort for users. They also have a disadvantage in terms of energy-saving because they wastefully heat the upper space in a room.
In addition, they maintain open the upper and lower outlet ports formed in their housing even when the corresponding air-blowing fans are not blowing out the conditioned air during their OFF mode. As a result, their housing has a great size in height and is not good in terms of design. They a further disadvantage in that dirt or debris comes into the housing through the outlet ports that are not blowing out the conditioned air such as cooled air.